.45 ACP Ballistics

[ASG]

Hi Everyone.

I have a fixed sighted 1911 that I have zeroed for Point of Aim/Point of Impact at 25 yards using 230 Grain ball ammo at around 850 FPS. I would like to shoot it at 50 yards using the same sight picture. My question is what bullet weight will allow me to achieve this? Right now the 230 Grain bullets are a couple of inches low at 50 yards, unless I aim higher, but I prefer the POA/POI sight picture. Thanks.

ASG

 

[Jerry Morris]

What you seek is not to be found easily. Each gun is unique and will shoot differently.

Seems to me you may be asking for more than a good pistolero needs. Windage and ranging are good talents to make your own. Knowing your gun and being able to almost automatically adjust to the known conditions are what you should be seeking.

For the .45 ACP, I want good 230 grain JHP, Hardball and RNL loads that shoots to the same POA. The rest will come from within myself. Changing bullet weights is asking too much from my point of view.

Jerry

 

[timbo]

This is actually an only-slightly-complicated physics problem. Maybe I'll get to it in the morning.

A lighter bullet however should shoot higher than your point of aim, which would result in a longer range shot for your point of aim due to the bullet's increased speed.

 

[TarpleyG]

Oh, contraire... A heavier bullet will shoot higher in most cases. At 50 yds., maybe not. The reason... heavier bullets take longer to come out of the barrel thus leaving at a higher point in your recoil. The distance may overcome that though. I do know that at 25 yds., a 1911 GM with a 185 gr. bullet hits lower than a 230 gr. I have tested it.

Hope this helps some. I know it sounds contrary to what you would think.

GT

 

[Lone_Gunman]

Timbo, the physics problem may only be slightly complicated, but I think you missed it anyway.

Read TarpleyG's post.

Heavy bullets shoot higher.

Lighter, faster bullets will shoot flatter, but not higher at typical handgun distances, because of the effect of recoil.

 

[fastbolt]

I suspect this is one of the very reasons someone invented rear sights that were adjustable for elevation ...

You might find yourself faced with the situation of either "raising" the front sight post in your "sight picture" to adjust for bullet drop at the farther distance, or have your pistol fitted with an ajustable rear sight, which may require a new front sight post, as well.

 

[Zak Smith]

Well, if we assume the gun was clamped in a vice, here's some relevant data:

 _BC_ _MV_         0      25      50 | YARDS
0.195  850 >   -0.41   -0.01   -2.49 | > Speer 230gr TMJ
0.138 1150 >   -0.41    0.67   -0.01 | > Speer 200gr GD/JHP
0.109 1160 >   -0.41    0.68   -0.02 | > Speer 185gr GD
0.138 1050 >   -0.41    0.51   -0.65 | > Speer 200gr GD/JHP
0.109 1050 >   -0.41    0.50   -0.71 | > Speer 185gr GD
0.138 1000 >   -0.41    0.41   -1.05 | > Speer 200gr GD/JHP
0.109 1000 >   -0.41    0.40   -1.10 | > Speer 185gr GD

Hope this helps.

 

[Lone_Gunman]

Zak:

I don't usually shoot my gun with it locked in a vice.

How is this supposed to help?

 

[Zak Smith]

Lone_Gunman,

Well, nobody else could post any useful data besides "try it and see."

If the bullet leaves the barrel before the handgun moves/rotates appreciably, the "in the vice" data should be close.

-z

 

[Archie]

ASG, tell me this.....

For what purpose is this load intended?

Are you shooting NRA 2700 bullseye or IPSC or self defense or what?

The actual question is: What degree of accuracy do you seek?

The answer may be simpler than you think.

 

[Chuck Dye]

ASG,

Take Zak Smith's ballistic coefficients and any other B.C.'s you may find and go to

http://www.norma.cc/htm_files/javapagee.htm .

Enter various B.C.'s and bullet weights into the define your own bullet option and play with the sliders. The answers you get will likely have only slight correlation with reality because of the way the gun behaves under recoil, but they are a start.

The best and only real answer is going to result from testing and will apply to the specific gun/ammo/shooter combination.

 

[Double Naught Spy]

What ASG is asking for is a near flat trajectory. The .45 acp round is not known for flat trajectories because of the heavy and slow factors. Some other pistol calibers such as 9 mm tend to be better at keeping a flatter trajectory.

Or, he wants the setup to be where the slug arcs and in the process hits POA at both 25 and 50 yards. The sights would need to be far enough above the barrel that the barrel is actually tilted slightly upward when the sights are level and on target. If attained, the round would travel slightly upward on the way to 25 yards, crest at 25 or slightly beyond, and then drop such that it hits the target at 50 yards in the same place. This is similar to sighting in an AR-15 at 25 and then having it also on target at 300. I don't know if you can get things to behave in such a manner between 25 and 50 yards.

 

[sctman800]

ASG, you don't mention reloading your own ammo, so I will assume you don't. Not only is this an interesting part of shooting for me, I can almost guarentee you won't save any money at it. You will however, get to shoot a lot more for the same amount of money, and with the available components you should be able to come up with loads that shoot where you want. Jim.